The infestation of food products by insects and insect larvae is well-documented. One particularly destructive pest is the Indian Meal Moth, Plodia Interpunctella, which is known to infest stored commodities, processed foods packaged for human consumption, and products produced for the pet food and birdseed markets. Infestations often remain hidden until the final larval stage, called the wandering phase, begins in which the larvae begin to search for a pupation site. Most Lepidopteran larvae become more tolerant of insecticides as they age. As a result, wandering-phase Indian Meal Moth larvae can be difficult to control.
Conventionally, coatings which repel insects, discourage feedance and deter oviposition have been implemented on food product packaging materials. For example, U.S. Pat. No. 5,843,215 to Whalon et al. is directed to coatings which comprise a water-based or water soluble resin and plant secondary compounds. The plant secondary compounds consist of those compounds which have insecticidal characteristics, such as insect repellence, antifeedance and oviposition deterrence.
U.S. Pat. No. 5,688,509 to Radwan et al. is directed to a controlled-release insect repellant device and a method for repelling insects from food, tobacco, or other consumable items. The device comprises an insect repellent composition contacting a substrate. The device is prepared by a method comprising applying the insect repellent composition to the substrate wherein the repellent compound used is present in the controlled-release insect repellent device in an amount such that when it is released it is non-toxic to humans and animals. The method for repelling insects comprises placing the controlled-release insect repellent device in an area where insects may be present. The insect repellent composition comprises a repellent compound and a controlled-release agent which comprises a compound which may be synthetic and/or natural, and, optionally, a solvent. The repellent compound may be chosen from the group consisting of essential oils and active ingredients of essential oils.
Although pesticidal compounds have been used with some success on food packaging materials, the toxicity of these compounds sometimes renders them unsuitable for use on food packaging materials. Some insect juvenile hormones, their analogues and their derivative compounds, present less toxicity than conventional pesticidal compounds. Juvenile hormones are insect growth regulators, which interfere with the developmental process of immature insects, but do not necessarily kill adult insects. In February 2002, the insect growth regulator methoprene was relabeled for stored commodities at application rates of 1, 2.5 and 5.0 wppm.
Methoprene and many other hormones are relatively volatile. As a result, conventional means for delivering pesticidal compounds may be undesirable for delivering hormones because the hormone may volatize at an undesirably fast rate thereby providing an unsatisfactory product lifetime. U.S. Pat. No. 7,250,396, the entirety of which is incorporated herein by reference, describes a hormone composition including a substrate having an external surface, and a coating layer including a polymer web, a UV protectant material, and from about 1 wppm to about 100,000 wppm of a hormone dispersed throughout the polymer web disposed on the external surface. A problem with many hormone containing coatings is that the hormone may be exposed to ambient conditions, which limits the effective active lifetime of the hormone.
Accordingly, the need exists for new packaging structures having desirable pest control delivery characteristics and product lifetime.